We will study the physicochemical properties of various lymphokines, including lymphotoxin, mitogenic factor and macrophage activating factor. Also, we plan to study a hypothetical hydrophobic peptide associated with the lymphocyte membrane that is believed to mediate the cytolytic action of lymphocytes. In addition, we plan to study the lymphocyte activating factor(s) of macrophages. We will attempt to isolate these agents in a high state of purity in order to perform difinitive studies on their mechanisms of action and on their roles in cellular immune phenomena in vivo as well as in vitro. Our long-term objective is the development of fundamental chemical and biological information in order to promote better understanding of the roles of these agents in infectious disease, in diseases of autoimmune origin, in allergic disorders, and in transplantation and tumor immunity.